From this panorama you can get a good impression how wide the Rhine is in some parts of the Rheingau. In this photo only the area on the left of the Rhine belongs to the Rheingau.
During the weekend, and especially when we have nice weather, the Rhine is full with boats. And there are also wind surfers which I've shown you earlier. Some people even swim in the Rhine, but you really need to watch out since there can be dangerous currents so you better go to beaches where it's allowed.